Metabolic correlates of fatal COVID-19. (A) Volcano plot demonstrating metabolite features differing in the plasma of individuals with severe or fatal COVID-19. The dashed line indicates an FDR of <0.05. (B) Differential abundance of progesterone, phosphocholine, lysoPC(16:0), and lysoPC(20:4) according to survival of severe disease or fatal outcome. (C) One-way hierarchical clustering based on significant metabolite features. (D) Mummichog modular analysis depicting a metabolic network of amino acids and derived metabolites. (E) Mummichog pathway analysis of significant metabolite features. (F) Differential abundance of oxoproline according to survival of severe disease or fatal outcome. (G) Reanalysis of the relative abundance of oxoproline along the course of 4 different time points before death due to COVID-19, retrieved from the study by Wu et al. (16). *, P < 0.05; **, P < 0.01; ***, P < 0.001.